Personally I like disagreement as it forces us to prove or backup statements.
By the way I have no issues with a flex as pictured on a micro hood.
If the grease is not vented at all it is a bigger hazard sitting under the cabinets over the flames.
That makes two.
OK, your turn Bob. When does a “micro” hood graduate to plain ol’ hood and then bump up to macro?
I know we aren’t code inspectors, but how does that justify ignoring code where it exists and and making up our own rules based on limited observations?
Code?
What code?
I am not a code Inspector but if we have no real world experience it is a good idea to base (BASE) opinion on national standards.
Since you are not an experienced appliance tech you are fine writing up this non issue as you see fit based on code books.
I am simply sharing what I know and IMO.
The more we can scare buyers the better ,right?
Now back to the start,please explain using your own noodle without books why grease buildup on the underside of a cabinet is safer than as pictured.
(you do know hoods are not required by code right)?
Most if not all “micro” hood manufactures have this on page 1 of their installation instructions.
“IMPORTANT – Observe all
governing codes and ordinances.”
Also, if there is not an exhaust hood then there is not a vent pipe. 
There are several jurisdictions around here (So Cal) that REQUIRE them
Then take this back…
I said using logic …nice try.
This vent pipe is connected directly to the exterior of the building. Is the pipe material okay, or should it be smooth wall galvanized steel, stainless steel, or copper? The NFPA recommends this type of material over open topped broiler in residential applications. Does a stove fall under the category of open topped broiler? :D:D:D:D:D:D:D:D:D:D:D:D:D:D:D:shock:
Attached Thumbnailshttp://www.nachi.org/forum/attachments/f20/50981d1325159521t-range-hood-vent-pipe-material-img_5305.jpg http://www.nachi.org/forum/attachments/f20/50982d1325159548t-range-hood-vent-pipe-material-img_5304.jpg
Would you say that having a smooth wall galvanized or stainless steel pipe is better/safer?
Certainly the immediate thought is smooth wall would be better since we have trapped lint on our minds from all the dryer discussions.
News flash ,the smooth wall sheet metal will also be coated in grease so I honestly do not think in a short run like this it matters much and the flex vent is very easy to replace compared to a solid tube that needs to be cut.
Do sparks travel past the hood?
Bigger concern would be a fire already in progress with giant flames which certainly would catch the cabinets on fire first.
Think about why cabinets are not required to be fireproof above stoves.
Maybe I am wrong but please logic rather than code to prove me wrong .
Sears made what you see pictured ,standard issue and still does as far as I know.
Although loggic dictates that smooth duct should be used, maybe all are being overly concerned with the flex duct.
This is a residential fan, not a Commercial kitchen exhaust.
Look at these statistics;
**[FONT=Times New Roman][size=4]Grease Hoods or Duct Exhaust Fans
[/size][/FONT]Grease hood or duct exhaust fans were involved in 1% of reported home cooking
equipment fires.
**During 2003-2006, U.S. fire departments responded to an average of 800 home structure fires
per year in which a grease hood or duct exhaust fan was involved in ignition. These fires caused
an annual average of 30 civilian injuries, and $6 million in direct property damage. These
incidents accounted for 1% of the reported home fires involving cooking equipment, 1% of the
associated civilian injuries, and 1% of the direct property damage from cooking equipment fires.
No civilian deaths were reported in these incidents.
Thanks Marcel.
No problem Bob, and Happy New Year to you. Hope you have a good Year. 
I could see a problem if it was into the attic to outside but sure is not a problem according to the picture posted.
Thanks also Marcel.
Put a blow torch against each type (quit reading into the situation) and see which one performs properly.
I don’t know where “directly to the outside” makes things better.?
The short run is closer to the source of ignition.
Immediate cold wall penetration will cause the condensation of grease and moisture causing greater buildup which is again, is closest to the ignition source.
Can you adequately clean a corrugated duct?
What a smooth duct be easier to maintain?
Is it better to have a vented range hood or a recirculating range hood?
If not maintained properly, any hood is a potential hazard.
At the end, none of this is really a concern of a home inspector.
So why don’t we just keep it a friendly discussion…
We can blow this all out of proportion and pretty soon the new guys will be calling this a building code violation.
Which collects grease faster and is likely to need cleaning more often? :roll:
Is flex duct even cleanable? I don’t think so.
There is flex duct like the crappy aluminum foil / wire style that you can stick your finger through that is pictured in this thread.
http://ecx.images-amazon.com/images/I/31GQd6yEJZL.SL500_AA300.jpg
or there is semi-rigid flex duct like this product.
One is crap, one is a good product.
Lol. This thread
Hope your heads are not smoking.
Goofy item to worry about and pseudo experts do not change that fact. So have fun pretending it is some major concern to scare buyers. With as I blow this pop stand.
Are you the real expert?
More so than you and Sears had us using them also which is a company with more experience in appliance installation than all the Inspectors combined sir.